Involvement of the esterase active site of egasyn in compartmentalization of beta-glucuronidase within the endoplasmic reticulum

Cell. 1987 Jul 17;50(2):301-10. doi: 10.1016/0092-8674(87)90225-x.

Abstract

Organophosphorous compounds, which are potent inhibitors of egasyn-esterase activity, caused a rapid dissociation of the high molecular weight egasyn-microsomal beta-glucuronidase complex when administered in vivo or when added in vitro to microsomal suspensions. The dissociation was relatively specific to phosphodiester inhibitors of the esterase active site. Also, the egasyn-esterase active site was inaccessible to substrates and to inhibitors when egasyn was complexed to beta-glucuronidase. Dissociation of the egasyn-microsomal beta-glucuronidase complex in vivo by organophosphorous compounds was followed by massive and rapid secretion of microsomal beta-glucuronidase, but not egasyn, into plasma. These experiments implicate the egasyn-esterase active site in attachment of microsomal beta-glucuronidase to egasyn by a novel mechanism that, in turn, compartmentalizes beta-glucuronidase within the endoplasmic reticulum.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Binding Sites
  • Carboxylic Ester Hydrolases*
  • Endoplasmic Reticulum / enzymology*
  • Endoplasmic Reticulum / ultrastructure
  • Esterases*
  • Glucuronidase / metabolism*
  • Kinetics
  • Liver / enzymology*
  • Liver / ultrastructure
  • Macromolecular Substances
  • Membrane Glycoproteins*
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred Strains
  • Models, Biological
  • Rats
  • Rats, Inbred Strains

Substances

  • Macromolecular Substances
  • Membrane Glycoproteins
  • Membrane Proteins
  • Esterases
  • Carboxylic Ester Hydrolases
  • egasyn
  • Glucuronidase